1. Field of the Invention
The present invention relates to an air ventilation structure for a shoe sole, and more specifically to an athletic shoe suitable for running, triathlon, and the like.
2. Description of the Related Art
The shoe sole is formed with a hole for air ventilation or drainage for preventing a foot from being hot and humid in the shoe is known.
FIG. 4 shows a structure of a shoe sole disclosed in Japanese Utility Model Laid-Open No. 143904/1989.
As shown in FIG. 4, the shoe sole 101 is formed with a number of vent holes 102. Each vent hole 102 has a hole diameter increasing toward the bottom in a tapered shape. Such shape allows foreign matter 103, such as a pebble, to drop off when clogged therein. However, even when the vent hole 102 is formed into such a tapered shape, the foreign matter 103 cannot drop off so easily. This results in the lowering of air ventilating and draining capabilities.
FIG. 5 shows a structure of a shoe sole disclosed in U.S. Pat. No. 904,891.
In FIG. 5, the shoe sole 101 supports an inner sole 105 via a coil spring 104. The inner sole 105 is formed with a number of ventilating openings 106. A guide-post 108 is fitted in the socket hole 107 formed on the shoe sole and supports the inner sole 105.
This related art is not suitable for a shoe to be worn for doing exercise, since the inner sole 105 moves upward and downward. FIG. 6 shows a structure of a shoe disclosed in U.S. Pat. No. 4,100,685.
The shoe sole 101 is formed with a number of venting channels 110 comprising through holes. The venting channel 110 is fitted with a filter insert 111.
In this related art, when foreign matter such as a pebble is caught in the lower portion 112 of the filter insert 111 of the venting channel 110, the foreign matter does not drop off, and is caught therein.
FIG. 7 shows a structure of a shoe disclosed in U.S. Pat. No. 4,507,880.
The shoe sole 101 is fitted with an air permeable member 120. The air permeable member 120 is formed with a number of ventilation through-holes 121.
In this related art, the ventilation through-holes 121 open on the bottom of the shoe sole 101. When small foreign matter such as a grain of sand is caught in the ventilation through-holes 121, the ventilation through-holes 121 can be clogged therewith.
Accordingly, it is an object of the present invention to prevent vent holes in a shoe sole from being clogged and to prevent the lowering of the air ventilating capability and the draining capability.
In order to achieve the object described above and others, the air ventilation structure of a shoe sole of the present invention is formed with a through hole vertically passing through the shoe sole. A ventilation part is slidably fitted into the through hole. The ventilation part comprises a flange portion and a projection. The flange portion engages with the upper surface of the shoe sole and is supported on such upper surface to prevent the ventilation part from dropping out of the through hole. The projection extends into the through hole partway. The projection is provided with a vent hole for the passage of air vertically therethrough.
When foreign matter such as a pebble enters from the bottom portion of the shoe sole and clogs the through hole therewith, the shoe sole is compressed when it is landed during exercise. In such a case, the ventilation part is not compressed. Therefore, the lower end of the ventilation part abuts against foreign matter, and the ventilation part pushes the foreign matter out downward, thereby preventing the through hole from being clogged.
In this way, according to the present invention, when foreign matter is caught in the through hole, it is pushed downward and out by the ventilation part when the sole is landed, and the foreign matter drops off. Therefore, there is little likelihood of the lowering of the air permeability and draining capability of the shoe sole.
In a preferred embodiment of the present invention, the through hole comprises a fitting hole portion defining the upper portion of the through hole for fitting the ventilation part therein, and a large diameter portion defining the lower portion of the through hole and having a larger hole diameter in comparison with the fitting hole portion. The projection passes through the fitting hole portion and extends into a part of the large diameter portion, so that the lower end of the projection faces toward an opening of the lower end of the large diameter portion.
In the preferred embodiment of the present invention, the large diameter portion is formed of a tapered portion which is gradually increased in hole diameter downward in a tapered shape, and the tapered portion opens downward.
According to this embodiment, the through hole gradually increases in hole diameter downward. Therefore, when the lower end of the ventilation part presses foreign matter from above after foreign matter is caught in the tapered portion, it can easily be dropped off.
In another preferred embodiment of the present invention, the upper surface of the shoe sole is formed with a fitting recess around the through hole corresponding to the shape of the flange portion.
According to this embodiment, by providing the fitting recess on the upper surface of the shoe sole, no irregularity is generated on the upper surface of the midsole, thereby improving comfortableness of the shoe.